BlackBerry Co-Founder Cuts Stake to Under 5%

Lazaridis Indicates He Doesn't Plan to Pursue Joint Bid for Company

TORONTO—BlackBerry Ltd. co-founder Michael Lazaridis disclosed in a regulatory filing on Tuesday that he reduced his combined stake with another co-founder in the smartphone maker to just under 5%, and indicated he no longer plans to pursue a joint bid to acquire the company outright.

In October, Mr. Lazaridis, and Douglas Fregin, another co-founder, disclosed they owned a combined 8% stake of BlackBerry and were considering a joint bid to acquire the Waterloo, Ontario, firm after it had put itself up for sale in August...